We derived simple analytical parametrizations for energy distributions of photons, electrons, and neutrinos produced in interactions of relativistic protons with an isotropic monochromatic radiation field. The results on photomeson processes are obtained using numerical simulations of proton-photon interactions based on the public available Monte Carlo code SOPHIA. For calculations of energy spectra of electrons and positrons from the pair-production (Bethe-Heitler) process we suggest a simple formalism based on the well-known differential cross section of the process in the rest frame of the proton. The analytical presentations of energy distributions of photons and leptons provide a simple but accurate approach for calculations of broadband energy spectra of gamma rays and neutrinos in cosmic proton accelerators located in radiation dominated environments.

• Received 5 March 2008

DOI:https://doi.org/10.1103/PhysRevD.78.034013